Metal propeller



' 1,635,840 July 12,1927. 1J. HAW

METAL PROPELLER Filed Jan. 15, 1925 2 Sheets-Sheet 1 4 Filed Jan, l5, 1925 2 Sheets-Sheet 2 l Patented vJuly. l2, 1927.

UNITED STATE/s PATENT" olif-'Leap1 .Taxon new, or FRIEDENAU, Naan BERLIN, GERMANY.

. METAL PBOPELLER.

Application n led January 15, 1985, SerialnNo. 2,584, and in Germany October 15, 1984.

This invention relates to metal propellers more particularly for use 1n aircraft. Y

One 'object of the invention 1s to provide a simple and practical construction of the metal blades and a connection of the blades with the propeller hub so that each blade can be turned about its longitudinal axis independently and thereby the blades given a greater or smaller pitch and each blade when adjusted can be fixed in thlspositron.

In the propeller of the present invention each blade is formed of a disk shaped casting of aluminium or 'aluminium alloy, which is open towards the flat side of the blade and this open side is closed by "a plate fixed on the shouldered edges of the casting, the under face of said plate resting on transverse and longitudinal ribs formed in the hollow interior of the casting and cast with the latter.

The innerend of the casting is closed over the entire periphery.l Each blade 1s firmly secured by means of a pair of steel rods to a circularly turned steel foot and xed together with this foot in the propeller` hub. This hub consists of two halves connected together by screws so that after the screws have been slightly slackened, each blade can be turned about its longitudinal axis by means of a settingl or adjusting de, vice and when adjusted, secured in its position by tightening up again the screws of the propeller hub.

One example of constructlon of the 1nvention is illustrated in the accompanying drawings, in which Fig. 1 is a view in elevation of a peller hub with one blade. I'

Fig. 2 a view showing theopen lnterior of the cast portion of the blade fixed to the foot by means of steel rods.

Figs. 3-7 are cross sections of the Afinished blade on lines indicated by- A, B, C, D, E, of Fig. 2.

Fig. 8 is a front view and Fig. 9 a side view of a propeller hub'on an enlarged scale with theblade feet revy olubly located therein.

Fig. 10 is a section of ,a blade on the line F-G of Fig. 8. l'

`The dished part 1 of the casting forming the blade which may consist of aluminium or aluminium alloy, for example, duralu. min, is providedI with a plurality of cross members 2. The lower end 3 of said blade is entirely closed and rests with a circularly turned part 30 upon a circular foot 4 being mounted in the hub and engaging by means of a flange 5 in a correspon-dingfannular groove in the hub. p

Two or more steel rods 6 having tapered shanksare mounted in the foot4.v Said steel rods 6 are passed throughall the cross vbars 2 and screw nuts 7 are screwed on the steel ro'ds at the cross bars, by means f which on the rotation of the propeller the tension exerted by centrifugal force on the material of the cast piece is transmitted to the steel rods. In order to enable the screw nuts to be firmly screwed against cross bars,

vand also on thecross bars 2 and the longitudinal rib 8. Said plate 12 which covers the dished part 1 of the blade is preferably not carried continuously to the point of the blade but only up to the outermost cross bar connected with the steel. rods 6. On this last cross bar a flange 14 is formed against which bears the front end of the cover plate l2. The result is that the centrifugal force on the plate set up by the rotation of the propeller is not taken by the screws or rivets 13 with which the plate 12 is secured to the edge 11 of the casting, but the plate bears dlrectly against the 'flange 14 of the last cross bar so that the centrifugal force actlng on the plate 12 is transmitted directly to the steel rods 6 by means of this cross bar. The point 15 of the blade is closed by a separate small cover plate 16. f

'The two edges of the dished part 1 of the casting are formed sufficiently thick to allow the perforations 17 necessary for the reception of the screws or rivets 13 to extend in thick material.

In order that the leading .edge of theA blade may not be .too heavy, said edge of the blade is cast in the form of a hollow fluting 10 so that firstly a considerable saving of material is effected and secondly the noise of the propeller is reduced. This is efected because when the propeller is running, the air contained in this hollow portion forms a kind of air cushion so that the hard material ofthe leading edgev of the blade no longer encounters the air, but the blade it self together with interpolation of the air cushion formed in the hollow fluting.

The hub mounted in the ordinary way on the propeller shaft 18 consists of two parts 19 and 20, four lugs 21 being provided on each half. Screws 22 are passed t-hrough the four pairs of lugs lying opposite one another on thetwo halt hubs. By tightly screwing up these screws the round turned foot 4 of the blade is firmly secured in the hollow cylindrical ends of the hub. f

If the pitch of the blades has to be altered, the two halt portions ofthe hub 19 and 2O which grip the feet 4 of the blades are released by loosening the screws 22 so that the blades carried by thefiange 5in the hub can now be turned and re-adjusted to any desired pitch.

In order to allow of 'saidadjustment of the blades to be effected with great exactness,

an arm 23 is provided on each half hub. Said arm'carries a screw pin 25 pivotally,

mounted thereon by means of an eyelet 24. A rib 26 is cast on the end 3 of the blade which is firmly connected with the foot 4. In this rib there is a slotted eyelet through which the screwpin 25 is passed. Screwrnuts 27 are mounted on both sides of the rib 26 on the screw pins 25. When the screws 22 are loosened, the respective blade may De turned in one or other direction about its lon itudinal axis as required by screwing baci one nut 27 and tightening up the opposite nut 27.

In order to be able "to determine exactly the extent of the rotation a scale 28 is provided on the blade foot opposite an 'indicatng mark 29 formed on the end of the hu After the pitch has been adjusted the feet of the blades are again firmly gripped between the two halves 19 and 20 of the hub by ti htening u the screws 22 and thus secure in their a justed position.

ing adished cast-ing formed with cross ars,

flange means on the edge of said dished part an upwardly projecting flange on said outer cross bar, a cover plate extending from the inner end of said dished part to said upward flan e and a plate covering the part of the dishe said upwardly projecting Hangs.4

3. A metal propeller' for aircraft comprising a'. dished castin closed at its inner end over its entire perip ery and having its lead- 'ing edge formed as a hollow groove, cross bars formed inthe hollow interior of said casting supporting shoulders formed on the said dished casting and cover plates for closing said dished casting.

4. A metal propeller for'aircraft compris ing a hub provided with aflongitudinally projecting stud, a blade formed of a dished casting, a foot firmly connected with said casting and rotatably mounted in the hub, a radially casting extending outwardly of.

projecting arm at the foot of the casting, a

threaded pin pivotally mounted on the rojecting stud of the hub and engaging wit ran eyelet provided in the radial arm of the casting, and a pair of nuts screwed onto the threaded portion of the aforesaid pin for locking the blade in adjustment. In testimony whereof, I have signed my ,namel to this specification at Berlin, Ger- December, 1924.

many, this 22nd day of JAKO B HAW. 

